I think some people are being a bit paranoid here. There is very, very little negatively in this thread. The original poster expressed an opinion that it looked pretty straight forward to build an ATC. A number of persons, myself included, pointed out that it may not be quite as simple as it may appear. Excellent cautionary advice in my book. It doesn't mean you give up it means you investigate further.
As a DIYer I have limited time available for this hobby, I therefore am very keen to avoid getting into projects that I don't have the time or the competence to complete, so I appreciate being alerted to such. Everybody is different of course.